Hi, to make hollow chocolate spheres, you would need two rigid plastic or polycarbonate molds. The flexi pan molds may be difficult to do, but Boulangere is correct in technique. You would have to temper your chocolate and fill both sides for a minute or so then dump them out and let them drain on a cooling rack. Once set, scrape and excess drips off with a paring knife and refrigerate for 30 minutes. When they come out, set aside and heat a cookie sheet to warm/slightly hot to the touch and barely melt the open ends and quickly attach the two. Wipe the excess off from the outside seam and let rest in a cool spot, or refrigerate for 10 minutes. There you have it.

If you want the cheap man's (or woman's!) method, take a shot glass, put some tempered chocolate in it and quickly swirl it around upside down so excess can run out. Not nearly as perfect or beautiful, so it depends on the occasion!